1. Technical Field of the Invention
The present invention relates to a display device substrate for use in a display device, a manufacturing method for manufacturing the display device substrate, a liquid-crystal display device incorporating the display device substrate, and electronic equipment incorporating the liquid-crystal device.
2. Description of the Related Art
Passive-matrix liquid-crystal devices include two panel substrates, each of which has a plurality of display electrodes running in parallel and wirings electrically connected to the respective display electrodes for applying the display electrodes with voltages. The two panel substrates are assembled to be opposed to each other in a manner such that the two panel substrates form a grating.
Active-matrix liquid-crystal devices having a thin-film diode (TFD) connected to each pixel are constructed by assembling a pair of substrates, i.e., an element substrate, and a counter substrate, in the mutually opposing position thereof. The TFDs, wirings respectively connected to the TFDs, and pixel electrodes serving as display electrodes are arranged on the element substrate. Arranged on the counter substrate is a plurality of display electrodes running in parallel, and wirings electrically connected to the respective display electrodes for applying the display electrodes with voltages. The element substrate and the counter substrate are assembled together in such a manner that the pixel electrodes on the element substrate are opposed in alignment to the display electrodes on the counter substrate.
As the definition of display becomes high, and the outline area surrounding a display area becomes narrow in these conventional liquid-crystal devices, the wirings respectively connected to the display electrodes become fine. As such a fine line design is currently introduced, the resistance of the wiring increases. A drop in the voltage applied from a drive circuit through the wiring is not negligible.
The passive-matrix liquid-crystal devices typically employ an STN (Super Twisted Nematic) liquid crystal. The display of such liquid-crystal display device is susceptible to a subtle variation in the drive voltage. The wiring is electrically connected to the display electrode and is physically continuous from the display electrode, and is fabricated of a transparent conductive film for use as the display electrode, such as an ITO (Indium Tin Oxide) film. The wiring is produced at the same time when the display electrodes are produced. As a result, the display electrode and the wiring thereof are fabricated of the transparent conductive film having substantially the same film thickness.
The wiring has a finer line width to meet compact design requirement. To reduce resistance in the wiring, an increase in the thickness of the transparent conductive film is contemplated. However, as the thickness of the wiring increases, the time required to form the film lengthens. As the wiring increases in thickness, the display electrode, which is concurrently produced, also increases in thickness. This leads to a reduction in the transmittance ratio of the display electrode.
In view of the above problem, the present invention has been developed. The present invention is thus designed to achieve at least one of the three objects of reducing electrical resistance in the wiring, increasing the light transmittance ratio of the display electrode, and shortening the time required to form the display electrode and the wiring.